Methods for the production of radiolabelled macromolecules, such as polypeptides, including proteins, peptides and antibodies are known in the art. Typically, traditional methods rely on either simple substitution reactions of subunits of the macromolecule's backbone, e.g. iodination of tyrosine in polypeptides, or organic chemistry to make derivatives which include a chelating entity, capable of avidly retaining radionuclides (usually metal ions), e.g. chelate derivatives of monoclonal antibodies.
For medical applications, the density of radiolabelling of polypeptides such as antibodies is a considerable problem, especially for imaging and therapeutic applications, which call for high levels of radioactivity in very small amounts of material. Also, if one needs to investigate the suitability of a range of different metal radioisotopes, the chelate chemistry has to be customised for each metal. It is therefore desirable to have a method of radiolabelling for macromolecules which can make use of a wide range of different metallic radioisotopes without substantial changes to the chemistry of radiolabelling. This would be especially valuable in medicine where radioisotopes have to be selected from the diversity of those available in order to determine those that are most suitable for different diagnostic and therapeutic applications.
There is a need for improved methods of preparing radiolabeled macromolecules that overcome or avoid one or more disadvantages or limitations of the known methods.